chore: fix typo (#4255)

Fix typo in quick start

beta/src/pages/learn/index.md

@@ -181,7 +181,7 @@ In the above example, `style={{ }}` is not a special syntax, but a regular objec
 
 ## Conditional rendering {/*conditional-rendering*/}
 
-In React, there is no special syntax for writing conditions. Instead, you'll use the same techniques as you use when writing regular JavaScript code. For example, you can an [`if`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else) statement to conditionally include JSX:
+In React, there is no special syntax for writing conditions. Instead, you'll use the same techniques as you use when writing regular JavaScript code. For example, you can use an [`if`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else) statement to conditionally include JSX:
 
 ```js
 let content;